Method and arrangement for measuring the density of natural fog in the free atmosphere using light source which is also a flashing warning beacon

Abstract

Abstract AN APPARATUS FOR DETERMINING THE DENSITY OF NATURAL FOG IN THE ATMOSPHERE IS DISCLOSED. IT INCLUDES A SPARK LAMP, WHICH ALSO HAS UTILITY AS A FLASHING WARNING BEACON, FOR PROJECTING A LIGHT BEAM OF CONSECUTIVE LIGHT PULSES OF CONSTANT AMPLITUDE THROUGH THE FOG-LADEN ATMOSPHERE. THE LIGHT PULSES ARE SCATTERED BY THE FOG TO PRODUCE CONSECUTIVE LIGHT PULSES PROPORTIONAL TO THE DENSITY OF THE FOG. A LIGHT PULSE RECEIVER HAVING ITS AXIS INTERSECTING THE AXIS OF THE TRANSMITTED BEAM RECEIVES THE SCATTERED LIGHT. A BLIND IS PROVIDED TO PREVENT DIRECT LIGHT FROM THE TRANSMITTER FROM REACHING THE RECEIVER. A LAYER OF FILTERS MAY BE PLACED IN FRONT OF THE PHOTOCELLS OF THE RECEIVER AS AN ADDITIONAL MEANS OF ELIMINATING LIGHT OTHER THAN THAT WHICH IS SCATTERED. THE PHOTOCELLS ARE UGROUPED INTO TWO GROUPS EACH OF WHICH IS A-C COUPLED TO ITS OWN PREAMPLIFIER BY MEANS OF A COUPLING CAPACITOR THEREBY EXCLUDING THAT PART OF THE PHOTOCELL OUTPUT WHICH IS DUE TO AMBIENT LIGHT. THE OUTPUT OF EACH PREAMPLIFIER IS CONNECTED TO A SEPARATE INPUT OF A COINCIDENCE STAGE SO THAT PHOTOCELL SIGNALS WHICH DO NOT OCCUR SIMULTANEOUSLY IN BOTH GROUPS OF PHOTOCELLS ARE INHIBITED. A MEASURING MEANS IS PROVIDED FOR MEASURING THE OUTPUT OF THE COINCIDENCE STAGE TO YIELD A INDICATION OF THE DENSITY OF FOG IN THE REGION BEING MONITORED.

Inventors

• 👤 Frank Fruengel

Bibliographic Details